<!DOCTYPE HTML>
<html class="reftest-wait">
<head>
<style type="text/css">
#rear {
  width: 500px;
  height: 1500px;
  box-shadow: 0 0 71px #667;
  display: block;
}
</style>
<script>
document.documentElement.scrollTop = 0;

function doTest() {
  document.documentElement.scrollTop = 108;
  document.documentElement.removeAttribute("class");
}
window.addEventListener("MozReftestInvalidate", doTest);
</script>
</head>
<body>
<div id="rear"></div>
</body>
</html>